In microwave systems such as communication systems and phased array antenna systems, microwave circuitry is often implemented in the form of what is commonly known as a microwave monolithic integrated circuit (MMIC). However, a MMIC is a relatively expensive device. For example, the entire MMIC circuit is implemented in a single substrate, which is typically gallium arsenide (GaAs). Gallium arsenide is a relatively expensive material, which costs approximately ten times as much as silicon. Further, since the entire circuit is implemented in a single substrate, and since the circuit typically includes several circuit components such as transistors for which the production yield is less than ideal, the percentage of chips obtained from a single production wafer without any significant defect can be on the order of only about 50% to 60%. Due to the number of defective chips which must be discarded, the effective production cost for the good chips is higher than would be the case if there was a higher production yield from the wafer.
A well-known alternative approach is commonly referred to as a hybrid circuit. In this approach, a portion of the overall circuit is provided on one substrate, such as a relatively expensive gallium arsenide substrate. The other portion of the circuit is provided on a different substrate, which is typically a cheaper material. The two substrates are then electrically coupled by bond wires that extend between bond pads provided on the substrates. While this hybrid approach has been generally acceptable for some applications, it has not been suitable for all applications. For example, in the case of a high frequency circuit, the bond wires exhibit parasitic inductance, and the bond pads exhibit parasitic capacitance. Consequently, there is still a need for a cheaper alternative to MMICs, which is suitable for applications such as high frequency microwave applications.